Damping means for tone generators



1953 F. H. SLAYMAKER ETAL 2,655,070

DAMPING MEANS FOR TONE GENERATORS Filed Dec. 4, 1950 2 Sheets-Sheet 1 yelocc'zgy J7 I r INVENTORS JX/ZWLL/ ma Oct. 13, 1953 F. H. SLAYMAKER EI'AL 2,655,070

DAMPING MEANS FOR TONE GENERATORS Filed Dec. 4, 1950 2 Sheets-Sheet 2 NVENTORS flu/2k ii Jay/marker Patented Oct. 13, 1953 UNITED; OFFICE $655,070 I; D M WGM IA S'F TONE "GENERA O S" Frank Slaymaker and. Willard FiMeeken. RoohestogN; Ya; assignors to Stromberg-Carlaonscompanyg a corporationzof: New )(orkt.

rn i fifiniflee mbe 4, .5 SeriMNm 19 956 #Glaims- (01. 84404) The present invention relates--' wdamping means for tone generators-and, moreparticularly, to damping means for tone generator-sof-the type employing an" elongatedmetallic" bar which is struck to produce tone" vibrationstherein'.

In certain musical instruments; such 'asthe electronic carillony which employa plurality of tone bars of different leng'th's an'dstrikenmeans for striking individually or -in groups arious ones of the bars, it often-happensthat-the vibrations set up-ina-particular tone bar are-sustained" so long that an annoying accumulation of after-ring builds 'up; This after rlng may I reach such a volume that it muddies u p"" all the music played on the carillon; This tendencytoward-=mud'diness is particularly troublesome wherr'note's are played in rapid succession; even thoujgh 'single note passages may sound very pleasing with the long after-ring; V V I I To eliminate the above described carry-over of the'vibrations; or muddinesspf"themusical passage, it is necessaryto reducethe decay-time of each tone bar by reducing'the-amplitud of the vibrations therein-by a-predetermined small amount during eachcycle-thereof so-that one tone'will have died out suflici'ently"before-the next tone is "struck to" prevent a-fte ringi'build up.

While it'is possible to damp the tone bar-by employing a" damping material which has rather 'high internal mechanical; loss; this type 'of damping reduces theamplitude or-thehigjherrrequenoy' partials much-more than-the-lower frequency components ofthe tones Moreover; when the tone generator is in the'form-of- 'anelongated cylindrical rod'clamped at one end; the-extremely high damping of the high frequencypartia'ls produces an unpleasant fclunky soundg and it is much more desirable- -from an esthetic point of view to damp the higher frequency'partials lss severely than the lower partials;

While certainarrangements heretofore l proposed have been employed' todamp' out com pletely the vibrations in certain mechanical elements such as relay contact springs orlong electrical transr'nission li'nes': or other mechanical systems in which?v it is desirable: completely to suppress vibrations; these arrangements are entirely I unsatisfactory for use a as R a damping means in connection with a: tone generator of the above-described type: wherein an" extremely small percentageof thestotal energy of the system is to be-reduc'ed during each'cyc'leof the tone generator. Thus. with' aconventional tone generator of the abowa descrihed: type'eit is 2 necessary only to -reduce the amount .or energy loss 'per'cycleby about .Zper cent forthe high frequency partials and by about one percent per cycle forthe=low frequency partials.

Accordingly, it is a primary object of the pres-- ent invention to provide new and improved damping means for a tone generator.

It is anotherobject of the present invention to provide new and improved tone generator dampingeneans whereby'the free andclear ringing of a::bel1 is simulated yet the *tone does-not'ring on soulong th'atinterference betweennotes is excessive.

It is a further 'ob'ject'ot the present invention to provide new an'd improved "damping means for a: tone generator of the above-described type wherein a predetermined small percentage of the vibratory energy of the generator is removedlduring each cycle of vibration thereof.

It is asti-ll'f-urther object of the-present invention to: provide new and improved damping means for a tone generator wherein the percentage change in the rateof: decay of the low frequency partials is greater than the percentage change of the high frequency partials,

It is another object of-"the present invention to provide newxand improveddamping means which may be employed with the tone generators of an electronic .carillonto damp the generators by a sufficient amount to prevent after-ring build up.-

It-is still anoth'erobjet 'of the present invention to provide-n'ew'and improved damping means for 1 a -ton'e generator of theabove-described type which maybe readily-adjustedto permit tuning of the generator without interfering with the damping action thereon It is a-'furthe'r obj ect of th'e present invention to provide new andimproved'damping means for a tonegenerator of I the above-described type wherein substantially uniform damping of all the frequency-components of "the tone is achieved, 1; e.-', the de'cay r'ate's of-allcomponents f are increased by the same number of db' persecond.

It isanothe'r objeot of the present invention torprovide newand improved "damping means for a --tone*generator wherein damping of a' partic'ular :frequency component oithe tone-is substantially eliminated,

It is 'stillanother object of the present invention to provide new and improved-damping means forztheitonegenerators of an electronic carillon which. cana'be addedxto existing instrum'ents having. 'undamped: tone generators :without substan tial change theretmr.

The invention, both as to its organization and method of operation, together with further obiects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view of a plurality of carillon-type tone generators which are provided with damping means constructed in accordance with one form of the present invention;

Figs Zw-Zjare diagrams useful to an under standing of the operation of the device of Fig. 1;

Fig. 3 is a timing diagram which further illustrates the mode of operation of the device of Fig. 1;

Fig. 4 shows an alternative embodiment of the invention;

Fig. 5 shows a further alternative embodiment of the invention;

Fig. 6 is a perspective view of a plurality of tone generators which are provided with damping means constructed in accordance with another form of the invention;

Fig. 7 shows an alternative form of the invention;

Fig. 8 shows still another form of the invention; and

Fig, 9 shows an additional form of the invention.

Referring now to the drawings and more particularly to Fig. 1 thereof, one embodiment of the improved damping means of the present invention is there illustrated as employed in a tone generator of the elongated cylindrical rod type having one end thereof securely clamped and the other end free to vibrate. Thus, a carillon base member It is used as a support for a plurality of elongated cylindrical tone bars I! and i2, each of which is securely clamped at one end thereof in the base member It by any suitable means such as the socket it, which is positioned in the base member is and'receives the end section of the bar ii. Each tone bar is struck at a point somewhat removed from the clamped end thereof by any suitable means such as a hammer 25.

In order to damp the tone bar i I there is pro- ;vided a small lightweight damping body in the form of a ring which encircles the free end of the tone bar ii. The damping ring 29 may be made of either an elastic or an inelastic material and has an inside diameter slightly larger thanthe outside diameter of the bar H. Ifan inelastic damping action is required the ring 2i} may be made of an inelastic material such as lead. For example, the ringiil may comprise one or two turns of fine wire solder whichis wrapped around the tone bar and twisted; In such an arrangement the clearance between the solder and the tone bar is very small and just that which normally occurs by virtue of the fact that the solder cannot be tightly twisted about the bar. If an elastic damping action is desired,

the damping ring 28 is preferably made of an elastic material. For example, the ring it may Moreover, we have successfully For example, a vinylidene-vinyl chloride copolymer such as known under the trade name Saran has been found satisfactory. For reasons to be discussed in more detail hereinafter, the clearance between the damping ring 28 and the tone bar i l is very small. .For example, with a tone bar of one eighth inch outside diameter it has been found that a damping ring of Phosphor bronze or other elastic material should have an inside diameter of 0.140 inch, i. e., a clearance between the ring and tone bar of 0.915 inch.

To prevent the damping ring 29 from moving longitudinally along the tone bar 5 I, a pair of restraining washers 22 and 2e are provided which are spaced apart so as to retain the damping ring therebetween while permitting limited longitudinal movement thereof. The washers 22 and 2 2 are preferably constructed of fibrous material and may be secured on the tone bar by first scale ing the washers in water and then pushing them over the end of the tone bar. When the washers dry they shrink to a very tight fit. How

ever, it will be obvious that other suitable means may be employed forsecuring the washers 22 and '24 to the tone bar;

"In considering the action of the damping ring 20 upon the vibrations of the tone bar i i it will be understood that irrespective of whether an elastic or inelastic material is employed, the mass of the damping ring iii is extremely small as compared to the mass of the tone bar ll. As the tone bar vibrates it carries the ring with it. However, due to the clearance between the ring and the tone bar which permits limited relative movement therebetween, impacts occur between the ring and the tone bar and some energy is lost from the vibratory system at each impact. While I prefer to employ an elastic damping body for reasons to be pointed out in more detail hereinafter, a qualitative discussion of the simpler damping action provided by an inelastic damping ring will be given before considering the action which obtains when an elastic ring is used.

When an inelastic impact occurs between the ring 2s and the bar ii, the two members remain together after the impact until the bar begins to slow down. The tone bar slows down after it passes the middle equilibrium position due to the increasing restraining force produced by flexion of the bar. As the bar slows down, the ring continues'to move in its original direction and with the maximum velocity obtained. If the clearance between the ring and the tone bar is small as compared to the amplitude of vibration of the bar, the ring overtakes the bar almost inimediately after the bar passes through its maximum velocity point and before the bar reaches its maximum displacement point. Thus, the collision occurs while the damping ring as and the free ber were traveling in opposite directions.

If the clearance between the dampingring and the bar is so large that the bar. can reverse directions between the instant that the bar and the ring separate and the instant that they col- .lide again, the damping is violent and completely destroys the vibrations of the tone bar in one or two cycles. Such a damping action is entirely unsuited for the control of musical tones.

However, in accordance withthe present invention and when an inelastic ring is'used, the clearance between the ring and the tone bar very small as compared to the amplitude of vibration of the tone bar. In this connection it will be understood that as the vibrations die out in the tone bar, a

situation willcccur at which the amplitude of vibration is, so small that the bar can change ,directionbefore the collision with the damping :gring takesiplace and a violent collision occurs due to thefactthattherifigand-bar are traveling in opposite directions: fiowevei in accordance with the resem investmentscl anses between the damping ring and the tone bar is? made small enough thata reversaloifdirction of the tone bar without collision does not-take place throughout the' audible" "portion of the tone. throughout the audible range of -the' tone bar vi brations the impacts-between the tone; bar and damping ring occur "while these members are traveling in the same direction, although at different-velocities, so that a very light'dam'ping action is producedand the pleasing qualities of the tone, particularly the high frequency partials thereof, are preserved although the overall decaytime of the tone issubstantially reduced to prevent'after-ring buildup; It will also'be understood that 'whentlie frictional forces'betweenthe restraining washers and the damping ring} he'- come larger than the acceleration forces, a*s'itu-- 'ation which obtains with low amplitude'vibra tions, no more impacts between the tone bar and the damping member will occur.

In order to illustrate more clearly theaction' of the damping ring 2mm providing a pred'eter mined small amount of damping for the tone-bar ll, referenceis nowmade to-Figs; 2a to"-'2,f,-inclusive, wherein the relative movement between these members is shown; Thus; referring to Fig, 2a, the bar 'H is shown at the'instant' just-after its reversal of direction and in its position oimaximum displacement.- In this position, one side of the tone bar I I isin contact with the inner surface ZS-ofthe-dampingring IQQa-nd the ring and bar aremoving together atjthe same speed. In the position shown in Fig. 2bthe bar has justreaohed its centergor equilibrium position; It willbe noted that thedamping-ringfZDyat thispoint in the travel of the'bari H, is-still sopositioned that the inner surface 25 ofthe ring is in contact with the bar. In the position shown in Fig. 2c, which-occurs'justslightlyafter the'bar has passed through the center equilibriumposition of Fig. 2b, the free'end-of-the bar has slowed down slightly althoughthe damping ring has continued to move at its previousvelocityso that the damping ring is now separated fromthebar.

In theposition shown in Figg 2d thedamping ring, which has been moving'at -agreater velocity than the free end-of-thetone bar, has overtaken thebar and movedto such a position that the rear inner surface 26: of the ring; collides with the other side of the hari H Thus, the ring iil, during the interval from Fig: 2b'to Fig. 2d frees itself from one side of -the ,ba r 'and 'then catches up with aridirhpinges upon theopposite side of the bar; The rear surface v2t oftheydamping ring remains in' contactwitlr the bar while the bar swings to the point of fmaximumdisplacement; asshow-n inFig; 2e at which point the bar is stationary. The damping ring and tone bar further remain in contact after the'bar' reverses direction as shown'in Fig. 2f, However; after the tone bar passesthroughgthe equilibrium position inthe' oppositedireotion, the damping ring ga n ara esianq"catches51in, w th; ,thepar,

that the, inner surface jof the ring again; con.

In the inelastic collision illustrated 111,. Figs Za-Zjf momentum is conserved, but energy, inso., far, as the motion of the members is concerned;

'two frequency componentspresent.

6' above, Fig; 3 shows-a graph of the-velocity of thefree end ofa tone bar in which there are In Fig. 3 the undamped velocity of the free end of the tone bar H isil1ustrated--bythe-dotted line 40; whereas the solid line M showsthe velocitywhen an inelastic damping ring 20-is positioned-in the manner described above'about' theireeend of the toneban- Consideringthe dampedcharacteristic H, it-is evident that just afterthe r tone bar passes the first equilibriumposition-with maximum velocity; as illustrated bythe dotted line 42; the tone bar begins to slow down'while the ringcontinues-to'trav'e1 at the samespeed so that thering oollideswith a'firstside-ofthe bar at the" point- 42'a, and remainsin contact with the bar until the next 1 equilibrium position occurs as indicated:'at-thedotted-line- 432" Just after the position 43 1 is reached, the -tone bar speeds up Y so that it-Iree'sitself from the damping ring-and continues to speed upuntiltheother's'ideof the bar contacts the damping- -ring at the-point 44. The damping ring and tone bar then remain in contact from the pointthrough the-next equilibrium position-- 45,- after--whioh point the tone-bar-slows down-while the'damping ring continues to travel at'th'e same-velocity so that 'the damping ring contacts the first side of the tone bar at the-point 46." The damping'ring andtone bar then remain in-contaot=from-the point 46 through the next equilibriumposition indicated bythe dotted line' 41, aftenwhichpoint the-same cycle of collisions betWeenthe-tone bar and the damping ringoccursr In thisconnec'tion it-will be understood that'the damping actionof theri-ng 20 is greatly exa gerated -in-'Fig.-3 to facilitate analysis thereof. In-action-practice the ring-2ii extracts a maximum of about 1%""of the-energy of the bar during each cycle of vibrationthereo'f;

It'will be noted from-the foregoing description that the inelastic damping action-which-obtains with a complex tone in which the damping ring first overtakes the tone barand'then the tone bar overtakes the ring; Howevemall of the im pacts between the tone--bar and damping ring occur while these members'are traveling-in the same direction. The diagrampf-Fig. Sis-based upon the assumptionthat the clearance between the inelastic damping gring and -the-tone bar is small as compared with the amplitude of vibra tionsof the bar. Itwillibe evident that such-a requirement is necessary-inorder to'pract-i-ce thepresent invention for-if theclearance between.

the tone bar and ringislarge the bar can reverse direction in the interval betweenthe" instant that the bar and ring separate-- and the instantthat they again collide;

If an elastic damping ring is employed in the arrangement shownin' Figyl, the-damping action. between thetone bar. andthedamping ring is more complex than if an inelastic" damping ring isused; If-the ring is verysma-llinmassas-com pared withthe mass of-the tone-bar-an'd if the ring/is struck by'the'bar when the bar is'traveling at a given velocity, thering' will bounce'away from' the bar at almost twice the velocity. ofthe bar; Traveling at this rate; the ring'soon overtakes the bar and bounces back again even though the clearancelbetwe'en the bar and ring is substantial. This bouncing back and forth can take place may times in the course of one'cycle of vibration of the bar. However, with smaller clearances the collisions take place more often and a heavier damping action is produ'ced. when the tone bar overtakes the ring and collideswith.

' that particular frequency component.

it, orwhen the ringand tone bar collidewhen traveling in opposite directions, the damping ring takes energy from the bar. Due to the elasticity of both the tone bar and the elastic ring 28 the amount of energy consumed during these impacts is very small. When the dampingring overtakes the tone bar and collides with it, some energy is restored to the tone bar from the damping ring. However, due to internal losses in the damping ring, and losses due to air viscosity, and the like, each collision results in a small loss of energy from the system. 7 Also, it has been observed that the elastic damping rings spin violently and climb up and down the ,7 tone bar within the limits imposed the restraining washers so that energy is also lost from the orderly state of vibrations within the bar to sustain this very random motion of the damping ring. Additionally, a certain amount of the energy is lostin friction between the damping ring and the tone bar as the ring spins and climbs up and down the bar.

The random character of the motion of the elastic damping ring is markedly different from the action of an inelastic ring. Due to the random motion ofthe elastic ring there is little frequency discrimination in the dampingefiected by the ring and approximately the same number of decibels per second is added to the decay rates of all of the frequency components which go to make up the composite vibration of the tone bar. Accordingly, when an elastic damping ring is employed the damping means of the present invention provides substantially uniform damping for all of the frequency components of the tone.

In considering the damping action achieved with either an elastic or an inelastic damping ring, it will be understood that the damping ring provides a subtle type of damping in which a very small amount of energy is extracted from the vibratory system during each cycle of oscillation thereof. Thus, "the lightweight damping body produces a gradual decrement of the tone vibration during each cycle and the high frequency partials are not excessively damped so that a very pleasing bell-like tone is provided although the overall decay rate of the tone is substantially decreased to avoid after-ring. Another advantage of the tone generator damping described above is that the damping bodies are of such small mass that the tuning of the tone bar is not noticeably altered thereby and the bars may be tuned independently of the action of the damping body thereon. Additionally, the damping means described above can be added to existing tone bar instruments, such as carillons, in a simple and economical manner without making other changes in the instrument, an advantage which is particularly desirable in eliminating after-ring in presently existing carillons.

The above-described damping means has 'the further advantage of permitting a particular tone partial to be accentuated. Thus, if the position of the damping ring corresponds to the node of a particular frequency component of the tone; the tone vibrations at that point will not include Accordingly, the damping ring will not affect this frequency component but will damp the remaining components in the manner described above so that the frequency component in question is accentuated. 7

While the damping ring has been illustrated positioned at the free end of the bar, it will be evident that effective damping control can also be obtained when the damping ring is positioned nearer the clamped end of the bar. Also, it will be evident that the damping body may comprise several rings in the event that a heavier damping action is desired.

in the alternative embodiment of the invention shown in Fig. 4, the damping ring 20 is positioned within a chamber Ell defined by a cylindrical enclosing member 5! which fits snugly over the free end of the tone bar Ii. The end walls 52 and 53 of the chamber 5| act as retaining washers to restrain the longitudinal movement of the damping ring. With this arrangement, the chamber 50 is sealed against dirt, and damage during use thereof is substantially prevented.

In the alternative embodiment shown in Fig. 5 t e use of retaining washers is eliminated and the tone bar 51 is provided with a section 69 of reduced diameter. A split damping ring GI, which is of small mass and of just slightly larger inside diameter than the reduced section 69 is then slipped over the reduced section and vibrates between the shoulders 62 and 63 which restrain the longitudinal movement of the damping ring. ihe damping ring 6! is preferably of elastic material so that it may be opened to permit insertion over the tone bar ii and the damping action thereof is identical to that described above in connection with Fig. 1.

In Fig. 6 there is illustrated another alternative embodiment of the invention in which the tone bars ii '52, each of which is securely clamped in the base member W, are provided with cavities in the upper ends thereof. The

tone bars ii and i2 may be secured to the base it by any suitable means such as the socketM, which receives the reduced neck 15 of the tone bar it. in the embodiment of Fig. 6, the damping body comprises a plurality of particles 86 which are loosely positioned within the cavity '33. The cavity is is sealed by any suitable means such as by the cover 52 which may be of cellophane tape or the like. The tone bar may be struck at a point somewhat removed from the clamped end thereof by any suitable means, such as the hammer to produce fundamental and overtone vibrations thereof.

For reasons to be discussed in more detail hereinafter, the particles as are preferably of a highly elastic material such as sand, and the number of particles positioned within the cavity '58 is extremely small. For example, in a tone bar having a cavity is approximately one-fourth inch deep and inch in diameter, it has been found that approximately fifty grains of sand having an average diameter of .5 millimeter will provide a suitable damping characteristic for an elongated cylindrical tone bar having an outside diameter of one-eighth inch and a length of seventeen and one-fourth inches.

7 When the tone bar ii is struck by the hammer 35, vibrations set up the bar so as to produce a fundamental tone and certain overtones as determined by the physical dimensions of the bar. Without considering the effect of the particles 63 which are positioned within the cavity 18, it will be evident that the vibrations set up in the tone bar H continue for a substantial period of time, the decay rate of these vibrations being determined by the internal, or inherent damping of the vibrator system; While it is possible to decrease the decay time of the tone bar I! by'using a damping material having a rather high internal mechanical loss, which is attached to the free end of the tone bar, this type of damping reduces the'high frequency components, or par {campin is suitable" forbom'pletedestruction of the vibrationsf'su'chas iredifird in ce'rta" 1 fchanial'isysteinsf'it 'doeshotffpioducei ubtle 'da'nip'ingof 'tlietonebararifdoes notpisive the brilliance and esthetic qualities of the tone. In accordance with the present invention, the particles 80 are preferably of a highly elastic material and an extremely small number of particles is positioned within the cavity ('8 so that in the main the particles do not slide over one another but instead collide directly with each other and with the walls of the cavity 18 to decrease the total energy of the vibratory system. Thus, part of the energy of the vibrating tone bar is lost at each collision of a sand particle with the walls of the cavity 18 and with each collision of one particle with another. Since both the silica particles and the steel tone bar are highly elastic the energy actually lost at each collision is extremely small. Other sources of energy loss include the viscosity loss as the sand travels through the air at a high velocity and the friction between sand particles that happen to graze by each other. However, due to the fact that an extremely small number of particles is employed, the energy loss due to friction between the particles is a small portion of the total energy and accordingly, the energy loss is not predominately in 'the high frequency region. Another energy loss which occurs is the conversion of the highly ordered energy, which is stored in the vibrating bar at very definite high frequency overtones, into the random, and hence useless, energy of the dancing sand particles.

While other finely divided materials can be used instead of sand for the damping particles 80, these materials are preferably elastic to reduce the frictional losses to a minimum. Large particles, such as steel shot, have been found unsatisfactory since they produce a rattling sound which detracts from the over-all tone brilliance and clarity.

While the provision of a plurality of elastic particles in a cavity located in the end of the tone bar is entirely satisfactory to produce a tone damping characteristic which is pleasing to the car, it is also necessary in the mass production of tone bars for electronic carillons and the like to provide means for varying the length of the tone bars so that they emit a tone of a particular fundamental frequency. To meet both of these requirements, the alternative embodiment shown in Fig. '7 may be employed. Thus, referring to this figure, the tone bar H is again provided with a cavity 18 in the end thereof, in which there .10 vis'rpositioned a plurality "of small elastic. particles r80 in.-"=the:':manneredescribed-in: connection-=with .iHoweventhe-cavityl8 ;isclosed byrmeans of a: plug imember 9 li having a-wreduced end por- ..5 tion SI -which--fits-snug=lyinto the "end .sofuthe cavity 1 8. With this-arrangement, a: -sufiicient :rnum'ber. of: particles" 80 maybe: positioned withe'ain athe --cavity -'l a properlytodamptheratone bar 7 [rafter which the plugr member'is inserted 'into 10:.the cavity 18 and the'end surface 92' of the plug t flliwis then ground 'oifva predetermined'-*ramount so as'to'tune-the .tonebar assembly tothe-desired efrequency.

In the alternative, the construction ofe-Figs B may: be employed swherein :the:.:particles 8 051 are positioned. atop :the free" endi-of the: tone; bar? I I aridearexenclosed7bymeans ofra cap memberr=95 eis providedrwith' a central cavity 96 therein. The

20 -cap 'srmembere 95 is: preferably of rawlightweight s plasticrsuch' asrpolystyrenec or the like, "and :is

pf slifficientlyesmall mass "so that it-doesi-noti af- 'fct the 'tun'ingfibf the tone bar. *Also, the::tun

ing of the bar may be made sufiiciently sharp without the cap 40 so that it will be correctly tuned with the cap in place.

Another alternative arrangement, shown in Fig. 9, consists in providing a hollow chamber 91 which slides over the end of the tone bar H and may be secured in place at the free end thereof by any suitable means, the chamber 91 completely enclosing the damping particles 80. The tone bar H is then tuned in the conventional manner by grinding off the free end of the bar without interfering with the receptacle 9! which holds the damping particles.

While there have been described what are at present considered to be the preferred embodiments of the invention, it will be understood that various modifications may be made therein which are within the true spirit and scope of the invention as defined in the appended claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a carillon or similar device, the combination of, a tone bar, means for striking said bar to produce tone vibrations therein, a damping ring of elastic material loosely encircling said bar, and means comprising two movable restraining members for limiting the movement of said ring along said bar, said ring having a small mass as compared with the mass of said bar to produce a gradual decay of said tone vibrations without excessively damping the higher partials of said tone.

2. In a carillon or similar device, the combination of, a tone bar, said bar having a neck portion adjacent one end thereof, said tone bar also having a substantially uniform cross-sectional area from said neck portion to the other end of said bar, means for striking said bar to produce tone vibrations therein, a damping ring of elastic material loosely encircling said bar, and two movable restraining members for limiting the movement of said ring along a portion of said uniform cross-sectional area of said bar, the maximum clearance between said ring and said tone bar being smaller than the maximum amplitude of vibration of said bar thereby to produce a gradual 7 substantially uniform increase in the rates of decay of all of the partials of said tone.

3. In a carillon or similar device, the combination of, a tone bar clamped at one end and having the other end free to vibrate, said tone bar having a substantially uniform cross-sectional area adjacent said other end and along the vibrating length of said bar, means for striking said bar to produce vibrations therein corresponding to a predetermined musical tone, a damping ring of elastic material loosely encircling said bar, movable washers for retaining said ring on said uniform cross-sectional area of said bar, said ring having a small mass relative to the mass of said bar, the maximum clearance between said ring and said bar being smaller than the maximum amplitude of vibration of said tone bar, thereby to produce a gradual substantially uniform increase in the rates of decay of all of the tone partials.

4.-In an electronic carillon or similar device utilizing a mass element, a tone bar, means for securing said tone bar to said mass element, a striker, means including said striker for vibrating said tone bar, the combination comprising: a damping ring of elastic material encircling said tone bar, two retaining members, said retaining members being positioned in spaced apart relationship on either side of said damping ring whereby said damping ring is afiorded freedom for movement along the length of said bar, the maximum clearance between said ring and said bar being smaller than the maximum amplitude of vibrations of said bar, thereby producing a gradual substantially uniform increase in the rates of decay of all partial tones.

FRANK H. SLAYMAKER.

WILLARD F. MEEKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,140,932 Young May 25, 1915 1,145,213 Remane July 6, 1915 1,843,553 Gladstone Feb. 2, 1932 2,155,052 Byland Apr. 18, 1939 2,180,539 Miller Nov. 21, 1939 2,195,041 Von Schlippe Mar. 26, 1940 2,302,670 Buchanan Nov. 24, 1942 2,375,818 Peters May 15, 1945 2,519,306 Zimmerman Aug. 15, 1950 Kunz Aug. 12, 1952 

